docs: def _check_soma_topology_swc(points):
      '''check if points form valid soma
  
      Currently checks if there are bifurcations within a soma
      with more than three points.
      '''
      if len(points) == 3:
          return
  
      parents = tuple(p[COLS.P] for p in points if p[COLS.P] != ROOT_ID)
      if len(parents) > len(set(parents)):
          raise SomaError("Bifurcating soma")